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Field Tested: Rab Generator Alpine Jacket


The Rab Generator Alpine Jacket is a lightweight, packable belay jacket designed for winter alpine mountaineering. It has a Pertex Diamond Fuse shell/exterior, weighs 540 grams (men’s medium), and comprises two layers of PrimaLoft® Gold Insulation with Cross Core™ Technology.


Lightweight // Durable fabric and stitching // Warm // Mobile // Helmet-compatible // Well-priced


Inside storage pockets could be a little bigger // A little long for my torso (I’m 5’7” and was testing a men’s M)

Our Thoughts

The Rab Generator Alpine Jacket is a high-quality synthetic jacket ideal for long, cold days when you need reliability: Its Pertex Diamond Fuse front fabric offered a durable and water-repellent fabric, which created a confident barrier between the rock, snow, and ice—as well as protected the PrimaLoft Gold Active+ insulation layer. Internally, the two weights of PrimaLoft created mobility by placing more fill in the body of the jacket and less in movement areas such as the armpits and hood. Meanwhile, large zipper pulls on the front, chest, and both hand pockets allowed for easy-access zippers even when wearing gloves or mittens, and pull drawstrings on the hood and waist made on-the-fly adjustments easy.

Size Reviewed

Men's M


540 grams





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A few months of winter field-testing revealed the Rab Generator Alpine Jacket to be a a high-quality synthetic belay puffy that proved ideal for long, cold days at the rock or ice when you need warmth and reliability.

A Durable Exterior

Let me start by saying I’m not an alpinist by any means. Most of my days out climbing consist of hiking into the Flatirons in Boulder, Colorado, and climbing sport. Still, these are mountains—even if front-country mountains—and things can get alpine up there pretty quickly, especially during or after a big storm or when the clouds and wind come in. I found myself needing a new warm belay puffy, so I was excited when Climbing asked me to test the Rab Generator Alpine Jacket.

I’ve always admired the Rab jackets my guide buddies at the Colorado Mountain School wore, and this was my first experience with the brand. Taking the Generator out of its lightweight stuff sack, I inspected the stitching, zipper, zipper pulls, elastic, and fabric. I immediately noticed the quality and thought Rab put into making this thing durable. The jacket just looked and felt well thought-out, reliably stitched, and with fabric a little more durable than other lightweight puffies I’ve owned in the past—you know, the ones you’re terrified to snag on something sharp like an ice tool or tree branch, because you know the exterior will tear.

Out in the field, I put the durability to the test, as I consistently rubbed up on sharp stone and tree branches on the approaches and while belaying, tossed the Generator on the ground more times than I can count, and allowed dogs to burrow into the jacket while seeking shelter on wet, snowy ground.

Rab Generator Alpine Jacket
Out testing on a snowy late-winter day in Colorado, in the Rab Generator Alpine Jacket.

Fit and Function

I really enjoyed the Rab Generator’s overall fit. It was large enough to layer over several midlayers (I’m 5’7, 150 pounds) and still felt roomy enough to stash extra food, gloves, and/or rock shoes in the pockets, to keep them warm between burns. My one gripe here is that when you have a pair of climbing shoes in the internal stash pockets (one on each side), it’s virtually impossible to use the two outer hand pockets. I feel like Rab could have added a wider internal pocket or a little more fabric to increase the space/give such that there’d be room for your hands or items in the external pockets when the internal pockets had large items in them. I was able to work around this by placing my climbing shoes a little higher in the internal pockets in order to make room for my hands in the exterior pockets.

The zippers and drawstrings all had large pulls, making it easy to access the pockets while wearing gloves and to adjust my hood. The Generator also has a bottom zip—as I would expect every belay jacket to have these days—in order to help you better access your belay loop.

I like my belay jacket to be a little large so I can layer underneath and tuck items inside to keep them warm, but even at that rate the Generator, at the size M I typically wear in puffies, seemed to run a little long and baggy for me, so perhaps I’d be a size small. However, I kind of liked the extra length when belaying single-pitch routes: With its longer hem, it provided extra warmth. However, while climbing, the extra length was a bit of a hindrance. I noticed this when I arrived at the cliff a little too early for comfort and decided to warm up climbing wearing the jacket. It almost felt like I was wearing a long and baggy shirt, which made it difficult to see my foot placements. Which is all to say, be attentive to sizing with the Generator, and consider dropping down a size from what you usually wear, especially if you plan to keep the jacket on for multi-pitch climbing, etc.

Rab Generator Alpine Jacket
The Generator Alpine Jacket in its stuffsack.

Running the Full Gamut of Conditions

Overall, during my two and a half months of testing, I was able to put the Generator Alpine through all types of conditions. From snowy, 15-degree-F ski tours, to 30-degree climbing days standing in the snow and shade, to standing exposed in 40 mph winds, I’ve come to agree with Rab that the Generator Alpine is a quality, well-made belay jacket you can trust in some of the harshest conditions.

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